POS1291 DEGENERATIVE DISC DISEASE IN YOUNG: IMMUNOHISTOCHEMICAL EXPRESSION OF INFLAMMATORY BIOMARKERS AND ANGIOGENIC FACTORS
Authors: N. Pravdyuk, N. Shostak, A. Novikova, A. Buianova, O. Patsap, A. Raksha, I. Senko, R. Tairova, A. Aksyonova, A. Muradyants, K. Davygora
Journal: Annals of the Rheumatic Diseases (2022)

Background Low back pain (BP), associated with the degenerative disc disease (DDD), poses a heavy social and economic burden, emerging among young adults. The pathophysiological basis of accelerated degeneration of the intervertebral disc (IVD) and its contribution to the formation of spine osteoarthritis are at the active study stage. Objectives To assess infammation and angiogenesis biomarkers in IVD among young patients with chronic LBP, associated with DDD. Methods Human IVD tissue from 25 patients was obtained from discectomy surgery to relieve LBP (men – 13, women – 12, age: 36,7 ±3,77) and from autopsy in healthy control group (n=5, age: 37,8±2,52). The grade of DDD was verified by magnetic resonance (MRI) by the classification of C.W. Pfirrmann. Four-micron serial sections of the tissue blocks were stained with hematoxylin and eosin (H-E), than examined by immunohistochemistry staining on the automated VENTANA BenchMark ULTRA platform. Anti-IL-1β, anti-IL-6, and anti-IL-17 were used to study the expression of inflammatory cytokines; anti-VEGF-A and anti-CD31 were used as markers of angiogenesis. All slides were visualized using a Axio Imager.Z2 microscope with EC Plan-Neofluar 40X objective. Results In 64% of patients IVD hernias were localized at the level of L5-S1, in 36% - L4-L5. The average Pfirrmann DD stage at the operated level was 4.43±0.57. 72% of patients had Modic changes (MC). 52% of patients had a combination of hernia with endplate erosion (EP) and MC. There were identified evidence of DD on H-E-stained sections, including clusters of cells of the nucleus pulposus (NP), inflammatory cell infiltration and blood vessels in the absence of them in the fissures of the NP and annulus fibrosus (AF). Immunostaining was mainly limited to the cytoplasm of native NP chondrocyte-like cells and AF fibroblast-like cells. IL-1β expression was considerably higher in degenerate samples than in controls for both NP (p &lt; 0,05) and AF (p &lt; 0,01). Staining for IL-17 was more pronounced in the cytoplasm of chondrocyte-like cells of degenerative NP compared to the control (p &lt; 0,01), and statistically lower in AF cells (p &lt; 0,05). The number of IL-6 immunopositive cells was similar in NP and AF degenerate tissue, but a greater proportion of IL-6 immunopositive cells was seen in NP tissue (p&lt;0,05). The percentage of cells immunopositive for VEGF-A and CD-31 was significantly increased in NP DD cell clusters compared to controls (p &lt; 0,001) (88% and 36%, respectively) and was weakly expressed in the extracellular matrix (p &lt; 0,05). This suggests that the PU cells trigger angiogenesis. Blood vessels in native sections were confirmed by CD31 detection in 64% of patient specimens versus 10% of control cartilage specimens (p &lt; 0,001). The number of CD31 immunopositive cells had a tendency for decrease in severe DD (p=0,05), which indicates the extinction of vascularization in the terminal stage of DD. Fissures in the disc did not stained for CD31, which excludes the ingrowth of vessels directly in the area of mechanical damage and proves the immunogenic cause of vascularization. This is confirmed by the synergistic high level of expression of IL-1 and -17 in perivascular, endotheliocytes and intravascular pathological samples versus weak expression in the disc matrix (p&lt;0.01).The high level of expression of all interleukins was in the hyaline cartilage of EP patients versus the absence in the controls (p&lt;0.001). It indicates their association with aseptic inflammation of EP with the formation of EP erosions and reactive spondylitis (MС) development, detected by MRI in young adults with DD. Conclusion Local immune inflammation is a component of the degenerative cascade in IVD, it initiates angiogenesis in cartilage and EP, as well as the development of reactive osteitis of adjacent vertebrae with the formation of inflammatory-erosive lesions of the vertebral-motor segment in chronic back pain. The results obtained will help to identify molecular targets and form a new direction of anti-inflammatory therapy of LBP among young people. Disclosure of Interests None declared